Mainspring tension indicator for watches and similar mechanisms



June 15, 1948. Q U FRENNESEN 2,443,558

' MAIN SPRING TENSION INDICATOR FOR WATCHES AND SIMILAR MECHANISMSF1ed.Ju1y 5, 1945 Patented June 15, 1948 MAINSPRING TENSI WATCHES AND SION INDICATOR FOR MILAR MECHANISMS Carl U. Frennesen, St. Paul, Minn.Application July 5, 1945, Serial No. 603,328

5 Claims. 1

This invention relates to means operable by the main spring of a watchor similar mechanism for indicating on a dial or scale the state oftension of the spring and/or for stopping an automatic spring windingdevice when the spring is fully Wound.

It is an object of my invention to provide simple, compact and efficientmechanism of this class whereby an observer is enabled to determine at aglance the state of tension of the main spring of a clock, watch orother mechanism having a rotary {spring-actuated member and a rotaryWinding member disposed in parallel and coaxial relation to Ithespring-actuated member.

A further object is yto provide a device of the class described adaptedto be applied as a simple attachment or addition to common types ofWatch mechanisms wherein a. main spring-driven member is disposedcoaxially with andin parallel relation to a wheel for Winding thespring.

A particular object is to provide mechanism of the class describedwherein movement is transmitted to an oscillatable arm from both thespring-driven member and winding wheel therefor through 4the medium ofteeth of spiral form and a toothed pinion which rotates about its owncenter and is movable substantially radially of the main spring axiswhile in mesh with the spiral teeth on the driven member and windingwheel.

Other objects will appear and be more fully pointed out in the followingspecication and claims.

Referring -to the accompanying drawing which illustrates my device byway of example and not for the purpose of limitation, as applied to aspring-operated watch mechanism of common type:

Figure 1 is a front view of the watch having a preferred form of myindicator mounted thereon and with -a portion of the face cover and dialbroken away to show parts otherwise concealed;

Fig. 2 is a back view of the mechanism with the cover removed;

Fig. 3 is a part side View and part section taken on the line 3 3 ofFig. 1;

Fig. 4 is a. fragmentary, somewhat diagrammatic, enlarged verticalsection taken approximately on the line 4-4 of Fig. 2;

Fig. 5 is a detail plan view of the spiral tooth carried by the ratchetwheel, looking in the direction indicated by the line 5-5 of Fig. 4 andwith 'the axial shaft shown in section;

Fig. 6 is a part plan view and part section taken approximately on theline 6 6 of Fig. 4, and

Fig. 7 is an enlarged plan view of a portion of the arm carrying thepinion and with the supporting arbor therefor shown in section.

As shown in the drawing, the watch has a case indicated generally by thenumeral 8, a removable back cover 9 and a transparent face cover orcrystal I0. The movement is supported within the case on aback plate I Iand parallel front plate I2 and there is a dial I3 supported in front ofthe plate I'2. These plates and the dial are rigidly connected togetherand to the case in suitable manner. A winding knob I4 projects from thecase to be manipulated to turn a gear I5 through suitable connectingmeans, including a stem and bevel gearing. The teeth of the gear I5 meshwith teeth formed on the periphery of a ratchet Wheel I6 and this wheelis fixed on a shaft I1 having bearings in the -plates II and I2 andconnected to the main spring of the watch (not shown) within the mainspring barrel indicated by the numeral I8. The main spring is of thecommon spiral form and has its inner end connected to the shaft Il andits outer end to the barrel I8 so that the latter is turned in onedirection (clockwise, Fig. 6) when the spring is under suicient tension.Peripheral teeth I9 on the barrel I8 are adapted to drive a suitablegear train to actuate, in the usual manner, the hands 20 indicating thetime by reference to the graduated dial I3. It will be evident that thewatch movement hereinbefore described is of common type illustrative ofsuitable environment for the preferred form of my improved indicatorpresently to be described.

I provide an arcuate scale 2I (Fig. l) on the dial I3 where it may bereadily observed through the crystal I 0 and a small hand 22 to indicatethe tension of the main spring by reference to the scale 2|. The latteris graduated and provided with indicia indicating at one end that thespring is fully wound and at the other end that it is unwound or hasinsuiiicient tension to operate the watch. There are also intermediateindicia abrding readings in fractions of full tension. The hand 22 isiixed on a pin 23 having a bearing in the front plate I2 and a smalltoothed pinion 24 is also fixed on the pin '23. This pinion is incontinuous mesh with a toothed segment 25 which is integral with an arm26 and the latter is fixed on an end of an arbor 2l. Bearings for thearbor 21 are formed in the plates I I and I2 so that Ithe arm 26 isadapted to oscillate upon the plate I2 about the axis of the arbor 2l.Details of the hand operating mechanism and scale 2l may be variedwidely Within the scope of the present invention.

A second arm 28 is connected to the arbor 21 and extends between theopposed faces of the ratchet wheel I6 and main spring barrel I8.Rotatable on the end of the arm 28 remote from the arbor 21 is a smalltoothed pinion 29, disposed with its axis of rotation parallel to andmidway between the opposed .faces of the ratchet wheel and drum. Thispinion is movable bodily with the arm `2B in an arc having its vvcenterat the axis of the arbor 21, this arc being approximately radial to theshaft |1 (see Fig. 6).

Formed on the face of the barrel I8 to mesh with the pinion 29 is aspiral tooth 30 havingits convolutions uniformly spaced radially .tocorrespond with the pitch of the teeth of 'the pinion 29. Another spiraltooth 3| is formed fon the ,Y

opposed face of the ratchet wheel the pinion 29 in a similar manner. VAslindicated in Figs. 5 and 6, the spiral tooth 3| winds .in the reversedirection as compared with the tooth 3|). That is to say, vfrom itsinner end 31a .the tooth 3| extends counter-clockwise .and Vspirallyoutward, whereas, .the tooth 39 extends clockwise from -its -inner endSta outward. The outer kends of the teeth 3@ and v3i are indicatedrespectively by the numerals T3817 and V3H). As further indicated inFigs. 4 and `6, lthe convolutions of the tooth 30 Acontinue-outwardsomewhat beyond Athe outer convolution 4'of the :tooth el randthe ,con-- volutions of the latter approach the shaft l1 more closelythan those of the tooth 3Q. Otherwise these teeth are vopposite one ,tothe other. lTlf-1e pinion 2S in its movement `about the axis of the-arb'or @2.1 oscillates substantially radially -oi the `spiral -teeth 30and .3l and is in continuous mesh with bothof them.

The connection between the arbor 21 and arm 2.8 is preferably or the:type shown in detail vin Fig. l7. Thus .the arbor Yis `of kelliptical.shape in cross section yand engages the iarm 28 in ,a substantiallysquare opening 32 in said arm.V A .slit 33 fbifurcates the end :portionof `said :arm which is constructed 'from sufficiently :resilientmaterial so 1that the respective end sportions :spring apart and permitslight oscillating movement of the arm relative to the arbor when thearbor is stopped through its connection with the-arm 25. Toflimitoscillating movement :of the arm .21.5, as indicated in Fig. 1, it maybe formed 'toextend between stop pins Sil and projecting from vthe faceof 'the supporting lplate I2. An angularly `bent end portion 38 `may-alsobe extended through an opening 35 in the plate l2 to aiiord'astopzfor 'the self-winding mechanism incase the watch is provided withautomatic winding mechanism.

In operation. when the watch is-*wound by Vmeans of -the `knob M, theratchet wheel H3 is turned in a clockwise direction (Figs. 2 and '5).Assuming that `'the main spring is in, fully unwound or low tensioncondition v'the .hand .-22 will point Ato Vthe Zero mark on the scale 2iand the corresponding position of .the 'pinion 29 will be at thel innerextremity scf the -tooth :34. Now as the watch fis wound the barrel itremains sub# stantially stationary the 4clockwise rotation of lthe wheelIt by means of the Itooth 3| causes the vpinion 2e vto .turn aboutitscenter and :to be moved substantially radially outward relative 'tothe shaft .|1. During this movement the pinion '29 merely vrolls in meshwith the convolutions =of Ui to mesh with the 'toothed and the 4arm 2liturns the arbor .'21 K and actuates the yarm 2t, tooth .segment 25 `and.piniont =tovmove the hand v22 -to the right (Fig. 1) `over the scale2|. lWhen .the main spring has been substantially fully wound in thismannerthe 4 arm 26 is stopped by the pin 35 with the hand 22 indicatingthe fully wound condition.

Overriding by the watch movement with respect to this fully woundposition of the arm 26 is permitted by so positioning the outer end 31hof the tooth 3| as to cause it to release the pinion 29 before thespring has been wound excessively tight. With the indicator hand 22 inthe fully Wound position the main spring slowly rotates the barrel i8 ina clockwise direction (Fig. 6) while the wheel H and its tooth 3| remainstationary. This causes the spiral tooth 30 to turn the pinion 29 and tooscillate the arm 28 radially yinward toward the shaft l1 with the axisof the arbor 21 as the center. Consequently the arbor 21 reverses themovement of the arm 26 which, through the segment 25 and pinion je,slowly moves the hand 22 to the left along the scale 2| from the fullywound position.

To permit overriding by the watch movement relative to the zero positionof the hand 22, the inner end 36a of the tooth S@ is so positioned Ithatit disengages the pinion 29 and stops inward movement kof ,the arm -28at a suitable point in the cycle of operation. Relief is also aorded bythe springing apart of the biiurcated yend portions of the arm 23relative to the elliptical arbor 27 thus allowing the arm 28 to swingslightly relative to the arbor, as indicated in dotted lines in Fig. 7.This feature is used to spring bias the arm 28 in an outward directionwhen released by the end @to of the tooth 3@ Aand in an inward directionwhen `released by the end 3|b of the tooth 3|. Thus the tendency of thearbor 21 to spring back to its diagonal position -in the square opening32 causes the pinion 29 to'rspring radially, to the extent of the radialpitch, outward when released by the inner end Sila of the tooth 3|) andinward when released by the end 3|b of the tooth 3l. The effect of thisis -to insure properengagement of the vpinion 29 with the spiral teethat all times.

'It will be evident that my device occupies space which is availablewithin the cases of ordinary watches and does not require rearrangementof the watch mechanism. The teeth 3B and 3| are preferably out on thefaces o1" the barrel t8 and wheel it respectively, although insomewatches it lmay be feasible 4torprovlde these spiral teeth on separatediscs or as separate spirals attached to the faces respectively ofspring driven and winding members. For `watches provided withself-winding de.- vices the end portion 3S of the arm 26, when in itsfully wound position constitutes `a stop for the oscillating weight,thereby'guarding against excessive winding and undesirable operationfofthe automatic winding movement. This stop feature may be used with orwithout the indicator hand and scale but it will Abe evident that theindicator shows when hand winding is necessary even where automaticwinding mechanism is provided.

Havingdescribed my invention, what I claim as new and desire to protectby Letters Patent is:

1. 'In a spring tension indicator for mechanism having a `rotaryspring-driven member, a spring for rotating said member and a rotaryspring Winding member disposed in spaced parallel and ycoaxial relationto said spring-driven member, .the improvements which comprise, teeth ofspiral form disposed on the respective opposed liaces of said .'members,a pinion movable substantially radially of the axis of .said membersbetween their opposed faces and Shaving teeth disposed to meshsimultaneously with the spiral teeth on said members, the tooth on saidwinding member being formed to move said pinion substantially radiallyin one direction during the spring winding rotation of said member, thetooth on the spring-driven member being' formed to move said pinionsubstantially radially in the reverse direction during the normalrotation of said spring actuated member and said spiral teeth -being ofrelatively unequal radial extent at their outer and inner ends to permitthe stopping of radial movement of the pinion While rotation of thespring-driven member relative to the winding member continues, meansincluding a scale and hand for indicating by reference to said scale thestate of tension of said spring and means connecting said pinion to saidhand for actuating said hand relative to said scale.

2. The indicator mechanism according to claim 1 in which stop means areprovided to limit the movement of said hand at the opposite endsrespectively of said scale and said means connecting said pinion to saidhand includes means associated with said stop means for resilientlyretaining said pinion in engagement with the spiral teeth during thereversal of movement of the pinion.

3. The indicator mechanism according to claim 1 in which said meansconnecting said pinion to said hand comprises an arbo-r disposed in Cilparallel relation to the axes of said members, an arm carried by saidarbor and extending -between said members, said pinion being rotatablymounted on said arm to impart oscillating movement thereto and meansoperatively connecting said arbor to said hand.

4. The indicator mechanism according to claim 1 which includes means forspring biasing the pinion radially inward when positioned at the outerextremity of its movement and radially outward when at the innerextremity of its movement.

5. The indicator mechanism according to claim 1 which includes an armpivoted to oscillate in a plane parallel to the opposed faces 0f saidspring-driven and winding members and operatively connected to saidpinion and means for limiting oscillating movement of said arm to an arccorresponding approximately to the radial movement of the pinion.

CARL U. FRENNESEN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 790,512 Mazer May 23, 1905790,513 Mazer May 23, 1905

